Extraction/insertion type soot blowing apparatus

Abstract

The present invention relates to an extraction/insertion type soot blowing apparatus in which a lance tube is inserted into a combustion chamber, and a high-pressure gas is blown from a nozzle provided at the tip end of the lance tube against a deposit adhered onto the inner surface of the combustion chamber to remove the deposit. A rack adapted to be advanced and withdrawn along with the lance tube, and a long shaft for rotating the lance tube, are driven due to connection thereof with two output shafts of a differential gear device, and rotation and linear motion of the lance tube are respectively restrained within predetermined ranges. Thereby, at first the lance tube is inserted into the combustion chamber at a high speed without being rotated, and thereafter the advance is stopped and a gas is discharged while the lance tube is being rotated. Accordingly, the time period in which the tip end portion of the lance tube is exposed to a high temperature is short, such that the lance tube does not become overheated.

What is claimed is: 
     
       1. An extraction/insertion type soot blowing apparatus, comprising: a support structure;   a lance tube mounted to said support structure, having a longitudinal axis, and being axially movable relative to said support structure to move forwardly from a start position to a predetermined position and to move rearwardly from said predetermined position to said start position;   a discharge nozzle mounted at one end of said lance tube, said discharge nozzle being directed in a direction substantially perpendicular to said longitudinal axis of said lance tube;   a rack disposed in parallel with said lance;   a pinion operable engaged with said rack;   a support plate fixedly secured to said rack and mounted to said lance tube such that said lance tube is rotatable relative to said support plate and axially fixed relative to said support plate;   an elongated shaft rotatably and axially movable supported by said support plate and disposed in parallel with said lance tube;   a differential gear device having an input shaft, a first output shaft connected to said pinion, and a second output shaft connected to said elongated shaft;   a rotary drive source operably connected to said input shaft of said differential gear device;   transmission means for transmitting rotation of said elongated shaft to said lance tube;   restraining means for restraining rotation of said elongated shaft when said lance tube is in an axial position rearwardly of said predetermined position;   prevention means for preventing said lance tube from advancing axially beyond said predetermined position;   feeding means for feeding a discharge medium into said lance tube when said lance tube is present at said predetermined position; and   wherein said restraining means comprises a guide mounted to said support structure in parallel with said lance tube, and a moving plate axially slidably and substantially non-rotatably supported by said elongated shaft, said moving plate having a slot formed therein which is engageable with said guide.   
     
     
       2. An extraction/insertion type soot blowing apparatus as recited in claim 6, further comprising a movable piece, mounted to said support structure, which allows said moving plate to rotate in one direction but prevents said moving plate from rotating in the opposite direction.   
     
     
       3. An extraction/insertion type soot blowing apparatus as recited in claim 1, further comprising a dog mounted to said lance tube for rotation therewith; and   a stationary limit switch, engageable by said dog, for reversing rotation of said lance tube when engaged by said dog.   
     
     
       4. An extraction/insertion type soot blowing apparatus, comprising a support structure;   a lance tube mounted to said support structure, having a longitudinal axis, and being axially movable relative to said support structure to advance from a start position to a predetermined position and to withdraw from said predetermined position to said start position;   a nozzle mounted at one end of said lance tube, said nozzle being directed in a direction substantially perpendicular to said longitudinal axis of said lance tube;   a rack disposed in parallel with said lance;   a pinion operably engaged with said rack;   a support plate fixedly secured to said rack and mounted to said lance tube such that said lance tube is rotatable relative to said support plate and axially fixed relative to support plate;   an elongated shaft rotatably and axially movably supported by said support plate and disposed in parallel with said lance tube;   a differential gear device having an input shaft, a first output shaft connected to said pinion, and a second output shaft connected to said elongated shaft;   a rotary drive source operably connected to said input shaft of said differential gear device;   transmission means for transmitting rotation of said elongated shaft to said lance tube;   restraining for restraining rotation of said elongated shaft when said lance tube is in an axial position rearwardly of said predetermined position;   prevention means for preventing said lance tube from advancing axially beyond said predetermined position;   feeding means for feeding a discharge medium into said lance tube when said lance tube is present at said predetermined position; and   wherein said feeding means comprises an opening/closing cam fixedly secured to said lance tube and having a notch, a linkage having a cam-follower adapted to engage said notch of said opening/closing cam when said lance tube is present at said predetermined position, and a head valve adapted to be actuated by said linkage to feed the discharge medium to said lance tube.